Liquid-crystal panel of polymer dispersed type, method of manufacturing the same, and liquid crystal display apparatus

ABSTRACT

A liquid-crystal panel comprises a pair of transparent glass substrates each being provided with an electrode. Between the glass substrates are disposed spacers for defining a space and a mixture of droplets of a liquid crystal having a mean diameter of 3.0 μm or less and of a photo-curing polymer. The edge portions of the glass substrates are sealed with a seal polymer. In curing the photo-curing polymer during the process of manufacturing the liquid-crystal panel, the dose of an ultraviolet ray is set to 500 mJ/cm 2  or more so as to reduce the diameters of the droplets of the liquid crystal, thereby preventing light leakage in the state without a voltage applied and improving the contrast. If the spacers are colored, the effect of preventing light leakage is increased. If the spacers are subjected to a surface treatment for rejecting the liquid crystal or composed of a polymer material of the same type as that of the photo-curing polymer, variations in diameter of the droplets of the liquid crystal can be prevented. With the structure, it becomes possible to provide a liquid-crystal panel in which light leakage in the black mode is reduced and which presents uniform and high-contrast display of images.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a liquid-crystal panel for usein a liquid-crystal display apparatus, an optical shutter, or the like,to a method of manufacturing the same, and to a liquid-crystal displayapparatus using the liquid-crystal panel.

[0002] Liquid-crystal panels, which are small in size, light in weight,and operable with low power voltage, have a wide range of applicationsas means for displaying a variety of visually recognizable patterns. Forexample, such appliances as wrist watches, electronic tabletopcalculators, personal computers, and personal word processors often useliquid-crystal panels therein for their further miniaturization andweight reduction. However, since a liquid-crystal panel of TN (twistednematic) type or STN (supertwisted nematic) type currently used requiresa polarizing plate, its light transmittance and long-term lightresistance are unsatisfactory. By contrast, since a panel containing apolymer dispersed liquid crystal (PDLC) does not require a polarizingplate, it is free from the above-mentioned drawbacks.

[0003] FIGS. 5(a) and 5(b) are cross-sectional views showing thestructure of a conventional liquid-crystal panel of polymer dispersedtype. FIG. 5(a) shows the state without a voltage applied, while FIG.5(b) shows the state with the voltage applied. As shown in FIGS. 5(a)and 5(b), the liquid-crystal panel is constituted by: a pair of glasssubstrates 1 a and 1 b having electrodes 2 a and 2 b, respectively,which are opposed to each other; and a mixture of a liquid crystal 4 anda photo-curing polymer 5 which is filled into the space between the bothsubstrates 1 a and 1 b. It is also possible to use a thermosettingpolymer instead of the photo-curing polymer 5, provided that it containsa crosslinkage-type polymer as its main component.

[0004] In a liquid-crystal panel of polymer dispersed type as describedabove, the liquid-crystal 4 is dispersed and held in the photo-curingpolymer 5 or the photo-curing polymer 5 exists in particles or innetwork in the liquid crystal 4. If a voltage is not applied to thespace between the electrodes 2 a and 2 b, liquid-crystal molecules arerandomly oriented so that a difference in refractive index is causedbetween the photo-curing polymer 5 and the liquid crystal 4, therebyscattering light (see FIG. 5(a)). On the other hand, if the voltage isapplied to the space between the electrodes 2 a and 2 b, theliquid-crystal molecules are oriented in the direction of a resultingelectric field so that there is a match in refractive index between theliquid crystal 4 and the photo-curing polymer 5, thereby transmittinglight (see FIG. 5(b)). Thus, the liquid-crystal panel of polymerdispersed type utilizes the phenomena of light scattering and lighttransmission. Spacers dispersed between the substrates 1 a and 1 b inorder to maintain a specified distance therebetween are composed of aninsulating material in spherical particles. Specifically, spacers madeof a transparent material such as SiO₂, benzoguanamine resin, ormelamine resin are used at present.

[0005] However, the above conventional liquid-crystal panel isdisadvantageous in that, when a voltage is not applied to theliquid-crystal panel, i.e., in the black mode, light scattering becomesunsatisfactory in the state shown in FIG. 5(a), so that a sufficientcontrast cannot be obtained. Even when the voltage is applied to theliquid-crystal panel, local variations are observed in lighttransmittance, resulting in uneven display of images.

[0006] In view of the foregoing, the present inventors have examined thephenomenon closely, which led to the following findings.

[0007] (1) The spacers composed of a transparent polymer materialpresents no problem if they are used in the liquid-crystal panel of TNtype or STN type. However, if they are used in the liquid-crystal panelof polymer dispersed type which utilizes the phenomena of lightscattering and light transmission, light scattering becomesunsatisfactory when a voltage is not applied, i.e., in the black mode,so that a sufficient contrast cannot be obtained.

[0008] (2) The use of spacers composed of an opaque colored polymermaterial, instead of a transparent material, is also under considerationas disclosed in Japanese Laid-Open Patent Publication Nos. 63-157130,1-144021, and 4-15623. Even with the spacers composed of a coloredmaterial, however, it is difficult to obtain a sufficient contrast.

[0009] (3) When a phase separation is caused by irradiating thephoto-curing polymer, which is a crosslinkage-type polymer, with lightor by heating the thermosetting polymer, liquid-crystal dropletsadjacent to the spacers become larger in size than those not adjacent tothe spacers. As a result, the application of a voltage causes adifference in light transmittance between the regions adjacent to thespacers and the other regions, so that a uniform displaying property maynot be obtained in a liquid-crystal display apparatus.

SUMMARY OF THE INVENTION

[0010] The present invention has been achieved in view of the foregoingand has the following objects.

[0011] The first object of the present invention is to provide aliquid-crystal panel in which a difference in light transmittancebetween the state with a voltage applied and the state without thevoltage applied is significant, i.e., a high-contrast liquid-crystalpanel by using liquid-crystal droplets and spacers with improvedstructures.

[0012] The second object of the present invention is to provide aliquid-crystal panel in which local variations in light transmittance inthe state with the voltage applied are reduced by using spacers with animproved structure.

[0013] The third object of the present invention is to provide aliquid-crystal display apparatus with an excellent displaying propertyby using a liquid-crystal panel with excellent characteristics asdescribed above.

[0014] To attain the above first object, a liquid-crystal panel with afirst structure comprises: a pair of substrates disposed so as to faceeach other, each being provided with an electrode for applying avoltage; spacers dispersed in the space between the above pair ofsubstrates so as to hold the above pair of substrates at a specifieddistance; a polymer member filled in the space between the above pair ofsubstrates, the above polymer member containing a crosslinkage-typepolymer as its main component; and droplets of a liquid crystal mixedwith the above polymer member and filled in the space between the abovepair of substrates, the above droplets of the liquid crystal having amean diameter of 3.0 μm or less.

[0015] With the above first basic structure, since the liquid crystal tobe filled in the space between the substrates in the liquid-crystalpanel is in fine droplets, the function of scattering light when avoltage is not applied is enhanced, so that light leakage via thedroplets of the liquid crystal seldom occurs. Consequently, a highcontrast can be obtained.

[0016] The above spacers can be provided with the function of preventingthe transmission of visible light. For this purpose, the spacers may becolored or the surface roughness of the spacers may be increased to adegree sufficient to scatter the visible light.

[0017] With the structure, light leakage via the spacers seldom occursin the black mode without the voltage applied, so that a higher contrastcan be obtained.

[0018] To attain the above first object, a first method of manufacturinga liquid-crystal panel comprises the steps of: preparing in advance apair of substrates each being provided with an electrode for applying avoltage and dispersing, on one of the above pair of substrates, spacersfor holding the substrates at a specified distance; holding the abovesubstrate on which the spacers are dispersed and the other substrate sothat they are opposed to each other with the spacers interposedtherebetween, mixing a polymer member containing a crosslinkage-typepolymer as its main component with a liquid crystal, and filling themixture into the space between the substrates; and promoting thecrosslinkage of the above polymer member, while causing a phaseseparation between the above polymer member and the above liquid crystalsimultaneously, so as to separate the above liquid crystal in dropletshaving a mean diameter of 3.0 μm or less. If a photo-curing polymer isused as a material for composing the above polymer member, inparticular, the above polymer member is irradiated with light equal toor intenser than 500 mJ/cm² in the step of promoting crosslinkage of theabove polymer member.

[0019] In the method, since the dose of light in the step of curing thephoto-curing polymer composing the polymer member has been set large,the cross-linking reaction of the polymer member is promoted, so that adistinct phase separation occurs between the liquid crystal and thepolymer member. Consequently, the droplets of the liquid crystal, whichhave been mixed with the polymer member, are miniaturized.

[0020] To attain the above second object, a liquid-crystal panel with asecond structure comprises: a pair of substrates disposed so as to faceeach other, each being provided with an electrode for applying avoltage; a polymer member filled in the space between the above pair ofsubstrates, the above polymer member containing a crosslinkage-typepolymer as its main component; droplets of a liquid crystal mixed withthe above polymer member and filled in the space between the above pairof substrates; and spacers dispersed in the space between the above pairof substrates so as to hold the above pair of substrates at a specifieddistance, the surface portions of the above spacers having at leasteither of a scarce affinity with the droplets of the liquid crystal anda large affinity with the above polymer member.

[0021] With the second structure, the effect of the liquid crystalmoving far away from the surfaces of the spacers becomes larger than theeffect of the liquid crystal moving closer to the surfaces of thespacers. Consequently, during the phase separation caused bycrosslinkage of the polymer material, the diameter of the droplet of theliquid crystal in a region adjacent to the spacer does not become largerthan the diameter of the droplet of the liquid crystal in a region notadjacent to the spacer. Accordingly, local variations in lighttransmittance of the liquid-crystal panel in the state with the voltageapplied are minimized.

[0022] In a specific structure of the above liquid-crystal panel withthe second structure, the surface portions of the spacers may be treatedso as to have the property of rejecting the liquid crystal.Consequently, the liquid crystal is kept away from the surfaces of thespacers in the liquid-crystal panel, so that the diameter of the dropletof the liquid crystal does not become particularly large in a regionadjacent to the spacer.

[0023] In another specific structure, at least the surface portions ofthe spacers are composed of a polymer material of the same type as thatof the above polymer member, with the result that the polymer memberpreferentially approaches the surfaces of the spacers. Consequently, thediameter of the droplet of the liquid crystal is not increased in aregion adjacent to the spacer.

[0024] It is also possible to add the above second structure to theliquid-crystal panel with the above first structure.

[0025] In the liquid-crystal panel with the above first or secondstructure, a photo-curing polymer can be used as the crosslinkage-typepolymer serving as the main component of the above polymer member.

[0026] With the structure, a phase separation is caused between thepolymer member and the liquid crystal by utilizing the cross-linkingproperty of the photo-curing polymer, so that an excellentdispersibility is imparted to the droplets of the liquid crystal.

[0027] A second method of manufacturing a liquid-crystal panel comprisesthe steps of: preparing in advance a pair of substrates each beingprovided with an electrode for applying a voltage and dispersing, on oneof the above pair of substrates; spacers for holding the substrates at aspecified distance, the surface portions of the above spacers havingeither a scarce affinity with droplets of a liquid crystal and a largeaffinity with a polymer member; holding the above substrate on which thespacers are dispersed and the other substrate so that they are opposedto each other with the spacers interposed therebetween, mixing the abovepolymer member containing a crosslinkage-type polymer as its maincomponent with a liquid crystal, and filling the mixture into the spacebetween the substrates; and promoting the crosslinkage of the abovepolymer member, while causing a phase separation between the abovepolymer member and the above liquid crystal simultaneously.

[0028] Specifically in the above second method of manufacturing aliquid-crystal panel, a surface-active agent containing fluorine as itsmain component is adsorbed by the surfaces of the spacers so that thesurface portions of the spacers have the property of rejecting the aboveliquid crystal or the spacers at least the surface portions of which arecomposed of a material of the same type as that of the above polymermember are used.

[0029] With the above method, the liquid-crystal panel with the secondstructure can be obtained.

[0030] To attain the above third object, the liquid-crystal displayapparatus of the present invention comprises in addition to theliquid-crystal panel with the above first or second structure: lightradiating means for irradiating the liquid-crystal panel with light; adriving circuit for applying an electric signal to the aboveliquid-crystal panel; and a displaying means for displaying the patternof light outputted from the above liquid-crystal panel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031]FIG. 1 is a cross-sectional view diagrammatically showing thestructure of a liquid-crystal panel according to a first embodiment;

[0032]FIG. 2 is a flow chart showing the process of manufacturing theliquid-crystal panel according to the first embodiment;

[0033]FIG. 3 is a cross-sectional view diagrammatically showing thestructure of the liquid-crystal panel according to a fifth embodiment;

[0034]FIG. 4 is a block diagram schematically showing the structure of aliquid-crystal display apparatus according to a sixth embodiment;

[0035]FIG. 5(a) is a cross-sectional view diagrammatically showing thephenomenon of light scattering caused by a polymer dispersed liquidcrystal when a voltage is applied thereto; and

[0036]FIG. 5(b) is a cross-sectional view diagrammatically showing thephenomenon of light transmission caused by the polymer dispersed liquidcrystal when the voltage is not applied thereto.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] First Embodiment

[0038] Below, a first embodiment of the present invention will bedescribed with reference to the drawings.

[0039]FIG. 1 shows a liquid-crystal panel according to the firstembodiment, which comprises: a pair of transparent glass substrates 1 aand 1 b opposed to each other; a pair of electrodes 2 a and 2 b providedon the respective inner surfaces of the glass substrates 1 a and 1 b soas to face each other; spacers 3 interposed between the glass substrates1 a and 1 b so as to hold the electrodes 2 a and 2 b at a specifieddistance; a liquid-crystal/polymer composite 6 composed of a liquidcrystal 4 and a photo-curing polymer 5 to be introduced into the spacebetween the glass substrates 1 a and 1 b; and a seal polymer 7 forsealing the edge portions of the liquid-crystal panel.

[0040] Below, a description will be given to a method of manufacturingthe liquid-crystal panel according to the first embodiment withreference to the flow chart of FIG. 2.

[0041] On the pair of transparent glass substrates 1 a and 1 b arepreliminarily formed the transparent conductive films (ITO films) 2 aand 2 b, each serving as an electrode. After cleaning the glasssubstrates 1 a and 1 b in Step ST1, spherical particles of SiO₂, eachhaving a diameter of 13 μm and colored with black, are dispersed as thespacers 3 on the electrode 2 a of the glass substrate 1 a in Step ST2,while the seal polymer 7 is printed on the edge portions of the otherglass substrate 1 b in Step ST3. These glass substrates 1 a and 1 b arebonded together with the spacers 3 and seal polymer 7 interposedtherebetween in Step ST4. The seal polymer 7 is cured in Step ST5 withthe application of heat.

[0042] Subsequently, in Step ST6, a mixture of the liquid crystal 4(which will be turned into droplets later on) and an ultraviolet-curingpolymer, which is a type of photo-curing polymer, is injected into thespace between the glass substrates 1 a and 1 b. The components of themixture are as follows:

[0043] liquid crystal

[0044] E-7 (commercially available from British Drug House Ltd.) (80 wt%)

[0045] ultra-violet curing polymer

[0046] mixture of polyester acrylate (1.8 wt %) and 2-ethylhexylacrylate (18 wt %)

[0047] photopolymerization initiator

[0048] Darocur-1173 (commercially available from Merck Ltd.) (0.2 wt %)

[0049] Next, in Step ST7, the liquid-crystal panel after injection isirradiated with an ultra-violet (UV) ray, thereby inducing across-linking reaction in the photo-curing polymer 5. The cross-linkingreaction in turn causes a phase separation between the liquid crystal 4and the photo-curing polymer 5 so that droplets of the liquid crystal 4are dispersed in the photo-curing polymer 5, while the photo-curingpolymer 5 is cured simultaneously. Thereafter, an injection hole issealed in Step ST8, thus completing the fabrication of theliquid-crystal panel.

[0050] Next, a description will be given to a test performed in order toelucidate the relationship between the doze of light for thephoto-curing polymer 5 and the mean diameter of the droplets of theliquid crystal 4.

[0051] Liquid-crystal panels were fabricated in accordance with theprocedure shown in FIG. 2. In this case, the dose of an ultra-violet rayfor the photo-curing polymer 5 was varied and set to 100, 200, 300, 400,500, 1000, and 2000 mJ/cm² for the respective liquid-crystal panels. Forcomparison, there was fabricated another liquid-crystal panel in whichcolorless and transparent particles of SiO₂ were scattered as thespacers.

[0052] These liquid-crystal panels were examined using a microscope andit was observed that the mean diameter of the droplets of the liquidcrystal 4 in the liquid panel irradiated with an ultraviolet ray of 400mJ/cm² or less in the curing step was as large as 5.5 μm or more, whilethe mean diameter of the liquid-crystal droplets in the liquid-crystalpanel irradiated with an ultraviolet ray of 500 mJ/cm² or more in thecuring step was as small as 1.0 to 3.0 μm. The contrasts of theliquid-crystal panels and the mean diameters of the droplets of theliquid crystal 4 therein were measured, the results of which are shownbelow in Table 1. TABLE 1 COLOR- LESS TRANS- PARENT SPACER BLACK SPACERDOSE OF 500 100 200 300 400 500 1000 2000 ULTRA- VIOLET RAY (mJ/cm²)CON- 53 25 37 46 51 98  108  110 TRAST MEAN 2.4 15.4 10.7 8.2 5.5 2.4  1.7   1.0 DIAME- TER OF LIQUID- CRYS- TAL DROP- LETS (μm)

[0053] It can be appreciated from the above Table 1 that theliquid-crystal panel using the colorless and transparent spacers is lowin contrast and unsatisfactory in the black mode compared with theliquid-crystal panel using the colored spacers. For example, if theliquid-crystal panel using the black spacers and the liquid-crystalpanel using the transparent spacers are irradiated with the sameultraviolet ray of 500 mJ/cm², the liquid-crystal panel with the blackspacers presents a high contrast of 98, while the liquid-crystal panelwith the transparent spacers has a low contrast of 53. This may bebecause light leakage in which the spacer transmits light occurs in theblack mode without a voltage applied.

[0054] The same tendency can be recognized even when the mean diameterof the droplets of the liquid crystal 4 is small. That is, if theliquid-crystal panels using the black spacers are compared with eachother, the mean diameter of the droplets of the liquid crystal becomeslarger as the dose of the ultraviolet ray is reduced. For example, ifthe dose of the ultraviolet ray is 500 mJ/cm², the diameters of thedroplets of the liquid crystal are surely 3.0 μm or less and thecontrast obtained is as large as 98 or more. By contrast, if the dose ofthe ultraviolet ray is 400 mJ/cm² or less, the mean diameter of thedroplets of the liquid crystal is as large as 5.5 μm or more and thecontrast obtained is as small as 51 or less. This may be because thelight leakage via the droplets of the liquid crystal 4 occurs in theblack mode, since the mean diameter of the droplets of the liquidcrystal 4 is large.

[0055] On the other hand, if the black spacers are used and the dose ofthe ultraviolet ray is increased so that an ultraviolet ray of 500mJ/cm² or more is applied in the curing step, a distinct phaseseparation occurs between the liquid crystal 4 and the photo-curingpolymer 5, so that the mean diameter of the droplets of the liquidcrystal 4 becomes as small as 3.0 μm or less. Consequently, lightleakage via the droplets of the liquid crystal 4 or via the spacers 3hardly occurs in the black mode.

[0056] Even when the transparent spacers are used, if an ultraviolet rayof 500 mJ/cm² is applied, the contrast obtained is higher than thecontrast obtained in the case where the black spacers are used but onlyan ultraviolet ray of 100 mJ/cm² is applied (53 versus 25). Hence, itcan be concluded that a mere reduction in size of the droplets of theliquid crystal 4 is effective to a certain degree in raising thecontrast.

[0057] Second Embodiment

[0058] Next, a second embodiment will be described.

[0059] The structure of the liquid-crystal panel in the secondembodiment is substantially the same as the structure of theliquid-crystal panel in the above first embodiment of FIG. 1, exceptthat the spacer 3 in the present embodiment is not spherical, but in theshape of a rod having a diameter of 10 μm and a length of 50 μm, thoughthe drawing thereof is omitted here. The rod-shaped spacer 3 is composedof a glass fiber colored with black. As for the other components, thestructures thereof are the same as those shown in FIG. 1.

[0060] A voltage was applied to the liquid-crystal panel thus fabricatedand the contrast and the mean diameter of the droplets of the liquidcrystal 4 were measured, the results of which are shown below in Table2. TABLE 2 COLOR- LESS TRANS- PARENT SPACER BLACK SPACER DOSE OF 500 100200 300 400 500 1000 2000 ULTRA- VIOLET RAY (mJ/cm²) CON- 53 21 29 41 4988  93  95 TRAST MEAN 2.4 21.0 14.3 9.1 6.2 3.0   2.6   2.0 DIA- METEROF LIQUID- CRYS- TAL DROP- LETS (μm)

[0061] In Table 2 is also shown the contrast of a liquid-crystal panelusing colorless and transparent spacers for comparison with theliquid-crystal panel according to the present embodiment. It will beappreciated from Table 2 that, even when the rod-shaped spacers aredisposed as in the present embodiment, the liquid-crystal panel usingthe black spacers and irradiated with an ultraviolet ray of 500 mJ/cm²or more in the curing step presents an excellent contrast of 88 or more.

[0062] Although the spacers were colored so that they function as meansfor preventing the transmission of visible light in the above first andsecond embodiments, the present invention is not limited to theseembodiments. If the surface roughness of the spacers is increased, lightis scattered by the surfaces of the spacers so that light leakage viathe spacers in the black mode can be prevented effectively.

[0063] Third Embodiment

[0064] Next, a third embodiment will be described.

[0065] The structure of the liquid-crystal panel in the third embodimentis basically the same as the structure of the liquid-crystal panel inthe above first embodiment (see FIG. 1), except that the surface of thespacer 3 shown in FIG. 1 is treated so as to adsorb a surface-activeagent containing fluorine as its main component. The spacer itself is ablack spherical particle of SiO₂ having a diameter of 13 μm and has thesame structure as that of the spacer 3 used in the above firstembodiment.

[0066] The process of manufacturing the liquid-crystal panel in thepresent embodiment is obtained by providing the steps shown in FIG. 2with an additional step of treating the surface of the spacer 3, thoughthe drawing thereof is omitted here.

[0067] Next, a description will be given to the manufacturing processbased on a test performed in order to elucidate the relationship betweenthe presence or absence of the surface treatment for the spacers and themean diameter of the droplets of the liquid crystal 4.

[0068] The liquid-crystal panels were fabricated in accordance with theprocedure shown in FIG. 2. In each of the liquid-crystal panels, theglass substrates 1 a and 1 b, electrodes 2 a and 2 b, spacer 3, liquidcrystal 4, photo-curing polymer 5, and seal polymer 7 are made of thesame materials as used in the above first embodiment. In the presenttest, however, the dose of the ultraviolet ray for the ultra-violetcuring polymer was changed to 1500 mJ/cm² and two types of spacers 3,one with the surface treatment for adsorbing the surface-active agentcontaining fluorine as its main component and the other without thesurface treatment, were used for comparison. In either case, thematerial and configuration of the spacers are the same and the spacersare composed of black spherical particles of SiO₂.

[0069] These liquid-crystal panels were examined using a microscope. Inthe liquid-crystal panel using the spacers without the surfacetreatment, the diameter of the liquid-crystal droplet in a region notadjacent to the spacer was about 1.5 μm, while the diameter of theliquid-crystal droplet in a region adjacent to the spacer was about 4.5μm, which was substantially tripled. On the other hand, in theliquid-crystal panel of the present embodiment with the surfacetreatment using the surface-active agent containing fluorine as its maincomponent, it was recognized that the diameters of the liquid-crystaldroplets in a region adjacent to the spacer as well as in a region notadjacent to the spacer are of the same order (about 1.0 μm) and uniform.A voltage was applied to these liquid-crystal panels so that theirrespective displaying properties were compared with each other. As aresult, the liquid-crystal panel using the spacers with the surfacetreatment of the present embodiment excellently presented a uniformdisplaying property, while uneven display of images was observed in theconventional liquid-crystal panel without the surface treatment.

[0070] Fourth Embodiment

[0071] Next, a fourth embodiment will be described.

[0072] In the present embodiment also, the basic structure of theliquid-crystal panel and the materials of the individual componentsthereof are the same as described in the above first embodiment (seeFIG. 1), except that the spacers 3 in the liquid-crystal panel of thepresent embodiment are composed of a polymer material of acrylic system,which is of the same type as that of the photo-curing polymer 5composing the liquid-crystal/polymer composite 6.

[0073] A voltage was applied to the liquid-crystal panel so that itsdisplaying property was compared with the displaying property of theconventional liquid-crystal panel with colorless and transparentparticles of SiO₂ dispersed therein. As a result, the liquid-crystalpanel of the present embodiment excellently presented a uniformdisplaying property, while uneven display of images was observed in theconventional liquid-crystal panel.

[0074] Fifth Embodiment

[0075] Next, a fifth embodiment will be described.

[0076]FIG. 3 is a cross-sectional view diagrammatically showing thestructure of the liquid-crystal panel in a fifth embodiment. In thepresent embodiment, the spacer 3 consists of a main body 3 a composed ofa SiO₂ particle and a surface portion 3 b for covering up the SiO₂particle forming the main body 3 a. The surface portion 3 b is composedof a polymer of acrylic system, similarly to the photo-curing polymer 5.That is, unlike the above fourth embodiment, only the surface portion ofthe spacer 3 is composed of a polymer material of the same type as thatof the photo-curing polymer 5. The structures of the other components ofthe liquid-crystal panel according to the present embodiment are thesame as those shown in FIG. 1.

[0077] A voltage was applied to the liquid-crystal panel so that itsdisplaying property was compared with the displaying property of theconventional liquid-crystal panel. As a result, the liquid-crystal panelof the present embodiment excellently presented a uniform displayingproperty, while uneven display of images was observed in theconventional liquid-crystal display.

[0078] Sixth Embodiment

[0079] Below, a sixth embodiment will be described.

[0080]FIG. 4 is a block diagram schematically showing the structure of aliquid-crystal display apparatus according to the sixth embodiment. Asshown in the drawing, the liquid-crystal display apparatus according tothe present embodiment comprises; a light source 11 composed of a metalhalide lamp; a UV/IR cutting filter 12; and three optical systems fordisplaying three colors, which are placed behind the light source 11 andUV/IR cutting filter 12. The three optical systems consist of dichroicmirrors 13 a, 13 b, and 13 c, liquid-crystal panels 14 a, 14 b, and 14c, lenses 15 a, 15 b, and 15 c, apertures 16 a, 16 b, and 16 c, andprojecting lens systems 17 a, 17 b, and 17 c. Each of the liquid-crystalpanels 14 a, 14 b, and 14 c is connected to a driving circuit, thoughthe drawing thereof is omitted here. The above three liquid-crystalpanels 14 a, 14 b, and 14 c use black spacers and were fabricated bysetting the dose of an ultraviolet ray in the step of curing thephoto-curing polymer to 2000 mJ/cm² so that the mean diameter of thedroplets of the liquid crystal becomes 1.0 μm.

[0081] Light from the light source (metal halide lamp) 11 is transmittedby the UV/IR cutting filter 12 and then separated into blue color, greencolor, and red color by the dichroic mirrors 13 a, 13 b, and 13 c, whichare incident upon the liquid-crystal panels 14 a, 14 b, and 14 c,respectively. After passing through the lenses 15 a, 15 b, and 15 c andthrough the apertures 16 a, 16 b, and 16 c, the three colors areincident upon the projecting lens systems 17 a, 17 b, and 17 c. When animage was projected with the use of the apparatus, excellenthigh-contrast display was obtained.

[0082] In addition, liquid-crystal panels using black spacers, in whichthe dose of the ultra-violet ray in the step of curing the photo-curingpolymer was set to 500 mJ/cm² and to 1000 mJ/cm², were fabricated andliquid-crystal display apparatus using the liquid-crystal panels werefabricated. In this case also, excellent displaying properties wereobtained. Similarly excellent displaying properties were also obtainedin the case where liquid-crystal display apparatus were formed by usingthe liquid/crystal panels with the structures of the above second tofifth embodiments.

[0083] It is not necessary for each of the pair of substrates disposedin the liquid-crystal panel of the present invention to be transparent.It is sufficient for at least one of the substrates to be transparent.The liquid-crystal display apparatus may have reflecting lens systems inplace of the projecting lens systems.

[0084] Although the mixture of polyester acrylate and 2-ethylhexylacrylate was used in each of the above embodiments, it is also possibleto use 2-hydroxylethyl acrylate, trimethylol-propane-triacrylate, andthe like. It is also possible to use a thermosetting polymer, instead ofthe photo-curing polymer, so that it reacts with the application ofheat. If a thermo-setting polymer of novolac system is used in thiscase, hexa-methylenediamine (hexamine) can be used as a curing agent.

[0085] The liquid crystal can be E-8 (commercially available fromBritish Drug House Ltd.), ZLI4792 (commercially available from MerckLtd.), TL202 (commercially available from Merck Ltd.), or the like. Thepolymerization initiator can be Irgacure 184 (commercially availablefrom Chiba-Geigy Ltd.), Irgacure 651 (commercially available fromChiba-Geigy Ltd.), or the like.

[0086] In other words, the present invention is effective irrespectiveof the liquid-crystal material and polymer material used.

[0087] A surface reforming agent for treating the surface of the spaceris not limited to the surface-active agent containing fluorine as itsmain component. A silane coupling agent (e.g., KA1003, KBC1003, KBE1003,KBM1003, KBM503, KBM303, KBM403, KBE402, KBM603, KBM602, KBE903, KBM573,KBM803, or KBM703, each commercially available from Shinetsu ChemicalCo., Ltd.; A-143, A-150, A-151, A-171, A-172, A-174, A-186, A-187,A-189, A-1100, A-1120, or A-1160, each commercially available fromNIPPON UNICAR Co., Ltd.; or SH6020, SZ6023, SH6026, SZ6030, SZ6032,SH6040, SZ6050, SH6062, SZ6070, SZ6072, SH6075, SH6076, SZ6079, SZ6083,SZ6300, AY43-021, PRX11, PRX19, or PRX24, each commercially availablefrom Toray Silicone Co., Ltd.), a silicone surface-active agent (e.g.,L-77, L-720, L-722, L-5310, L-7001, L-7002, L-7500, L-7600, L-7602,L-7604, L-7607, or Y-7006, each commercially available from NIPPONUNICAR Co., Ltd.), a silane monomer (e.g., A-162 or A-163, eachcommercially available from NIPPON UNICAR Co.,), a silicone primer(e.g., AP-133, Y-5106, Y-5254, or APZ-6601, each commercially availablefrom NIPPON UNICAR Co.,), a coupling agent of titanate system (e.g.,PLENACT, KRTTS, KR38S, KR44, KR46B, KR55, KR138SS, KR238S, 338X, KR2S,KR7, KR9S, KR11, KR12, KR34S, or KR41B, each commercially available fromAJINOMOTO CO., INC.), a coupling agent of aluminum system (e.g., AL-Mcommercially available from AJINOMOTO CO., INC.), a surface-active agentof amino acid system (e.g., AMISOFT or CAE, each commercially availablefrom AJINOMOTO CO., INC.), an agent for homeotropic orientation (e.g.,DMOAP or ODS-E, each commercially available from Chisso Corporation), orthe like is also effective. If colored spacers are subjected to thesurface treatment, light leakage in the state without the voltageapplied is eliminated, so that the contrast is further improved.

[0088] To color the spacers, there can be used any of the method ofcoloring by means of a dye, the method of having an organic substanceadsorbed into minute holes in the spacers so that it is carbonized bysintering, the method of sputtering fine black particles into thespacers, and the like.

[0089] It is also possible to use an active-matrix substrate composed ofactive elements provided on one of the electrode substrates.

We claim:
 1. A liquid-crystal panel comprising: a pair of substratesdisposed so as to face each other, each being provided with an electrodefor applying a voltage; spacers dispersed in the space between said pairof substrates so as to hold said pair of substrates at a specifieddistance; a polymer member filled in the space between said pair ofsubstrates, said polymer member containing a crosslinkage-type polymeras its main component; and droplets of a liquid crystal mixed with saidpolymer member and filled in the space between said pair of substrates,said droplets of the liquid crystal having a mean diameter of 3.0 μm orless.
 2. A liquid-crystal panel according to claim 1 , wherein saidspacers have the function of preventing the transmission of visiblelight.
 3. A liquid-crystal panel according to claim 2 , wherein saidspacers are colored.
 4. A liquid-crystal panel according to claim 2 ,wherein said spacers have a surface roughness sufficiently high toscatter visible light.
 5. A liquid-crystal panel according to claim 1 ,wherein the surface portions of said spacers have at least either of ascarce affinity with the droplets of the liquid-crystal and a largeaffinity with said polymer member.
 6. A liquid-crystal panel accordingto claim 5 , wherein the surface portions of said spacers are treated soas to have the property of rejecting said liquid crystal.
 7. Aliquid-crystal panel according to claim 5 , wherein at least the surfaceportions of said spacers are composed of a polymer material of the sametype as that of said polymer member.
 8. A liquid-crystal panelcomprising: a pair of substrates disposed so as to face each other, eachbeing provided with an electrode for applying a voltage; a polymermember filled in the space between said pair of substrates, said polymermember containing a crosslinkage-type polymer as its main component;droplets of a liquid crystal mixed with said polymer member and filledin the space between said pair of substrates; and spacers dispersed inthe space between said pair of substrates so as to hold said pair ofsubstrates at a specified distance, the surface portions of said spacershaving at least either of a scarce affinity with the droplets of theliquid crystal and a large affinity with said polymer member.
 9. Aliquid-crystal panel according to claim 8 , wherein the surface portionsof said spacers are treated so as to reject said liquid crystal.
 10. Aliquid-crystal panel according to claim 8 , wherein at least the surfaceportions of said spacers are composed of a polymer material of the sametype as that of said polymer member.
 11. A liquid-crystal panelaccording to claim 1 , wherein said polymer member is composed of aphoto-curing polymer.
 12. A method of manufacturing a liquid-crystalpanel comprising the steps of: preparing in advance a pair of substrateseach being provided with an electrode for applying a voltage anddispersing, on one of said pair of substrates, spacers for holding thesubstrates at a specified distance; holding said substrate on which thespacers are dispersed and the other substrate so that they are opposedto each other with the spacers interposed therebetween, mixing a polymermember containing a crosslinkage-type polymer as its main component witha liquid crystal, and filling the mixture into the space between thesubstrates; and promoting the crosslinkage of said polymer member, whilecausing a phase separation between said polymer member and said liquidcrystal simultaneously, so as to separate said liquid crystal indroplets having a mean diameter of 3.0 μm or less.
 13. A method ofmanufacturing a liquid-crystal panel according to claim 12 , wherein aphoto-curing polymer is used as a material composing said polymer memberand said polymer member is irradiated with light equal to or intenserthan 500 mJ/cm² in the step of promoting the crosslinkage of saidpolymer member.
 14. A method of manufacturing a liquid-crystal panelcomprising the steps of: preparing in advance a pair of substrates eachbeing provided with an electrode for applying a voltage and dispersing,on one of said pair of substrates, spacers for holding the substrates ata specified distance, the surface portions of said spacers having eithera scarce affinity with droplets of a liquid crystal and a large affinitywith a polymer member; holding said substrate on which the spacers aredispersed and the other substrate so that they are opposed to each otherwith the spacers interposed therebetween, mixing said polymer membercontaining a crosslinkage-type polymer as its main component with aliquid crystal, and filling the mixture into the space between thesubstrates; and promoting the crosslinkage of said polymer member, whilecausing a phase separation between said polymer member and said liquidcrystal simultaneously.
 15. A method of manufacturing a liquid-crystalpanel according to claim 14 , further comprising the step of treatingthe surface portions of said spacers so that they have the property ofrejecting said liquid crystal.
 16. A method of manufacturing aliquid-crystal panel according to claim 15 , wherein, in the step oftreating the surface portions of said spacers so that they have theproperty of rejecting the liquid crystal, a surface-active agentcontaining fluorine as its main component is adsorbed by the surfaces ofthe spacers.
 17. A method of manufacturing a liquid-crystal panelaccording to claim 14 , wherein the spacers at least the surfaceportions of which are composed of a material of the same type as that ofsaid polymer member are used.
 18. A liquid-crystal display apparatuscomprising: a liquid-crystal panel; light radiating means forirradiating said liquid-crystal panel with light; a driving circuit forapplying an electric signal to said liquid-crystal panel; and adisplaying means for displaying the pattern of light outputted from saidliquid-crystal panel, wherein said liquid-crystal panel comprises: apair of substrates disposed so as to face each other, each beingprovided with an electrode for applying a voltage; spacers dispersed inthe space between said pair of substrates so as to hold said pair ofsubstrates at a specified distance; a polymer member filled in the spacebetween said pair of substrates, said polymer member containing acrosslinkage-type polymer as its main component; and droplets of aliquid crystal mixed with said polymer member and filled in the spacebetween said pair of substrates, said droplets of the liquid crystalhaving a mean diameter of 3.0 μm or less.
 19. A liquid-crystal displayapparatus comprising: a liquid-crystal panel; light radiating means forirradiating said liquid-crystal panel with light; a driving circuit forapplying an electric signal to said liquid-crystal panel; and adisplaying means for displaying the pattern of light outputted from saidliquid-crystal panel, wherein said liquid-crystal panel comprises: apair of substrates disposed so as to face each other, each beingprovided with an electrode for applying a voltage; a polymer memberfilled in the space between said pair of substrates, said polymer membercontaining a crosslinkage-type polymer as its main component; dropletsof a liquid crystal mixed with said polymer member and filled in thespace between said pair of substrates; and spacers dispersed in thespace between said pair of substrates so as to hold said pair ofsubstrates at a specified distance, the surface portions of said spacershaving at least either of a scarce affinity with the droplets of theliquid crystal and a large affinity with said polymer member.